November 1, 2015
by Goth Siu, BHSc, DMD, MS, Cert. Prostho., FRCD(C)
Advances in dental implant research, design and their clinical application have greatly changed dental care. Improved protocols in implant therapy over the last several decades have made implant supported restorations biologically and mechanically predictable.1-5 However, there is still a role for conventional tooth supported fixed dental prostheses.6 Full arch implant-supported restorations are increasingly popular, but many patients are not psychologically ready for the extractions and alveolectomy that is often required. The following case presentation demonstrates the combined use of dental implants and tooth supported fixed dental prostheses to restore the patient’s esthetics and function.
The patient presented with the chief complaint of poor esthetics and difficulty in mastication. The patient reported having hypertension and hyperlipidemia, which was treated and controlled by the patient’s physician. The patient smoked one pack a day but quit nine years ago. Many years of infrequent dental visits had resulted in a loss of many posterior teeth. The loss of posterior support, compounded with caries, periodontal disease, attrition and fracture, led to the loss of vertical dimension, extrusions, malpositions and a compromised plane of occlusion.
FIGURE 13. Left view of provisionals at maximum intercuspation
FIGURE 20. Custom impression copings accurately capture the soft tissue profile and transfer that information to the laboratory technician. It also splints open tray impression copings together during the impression.
Alginate impressions were taking to fabricate diagnostics casts after a comprehensive extraoral and intraoral exam. After determination of the etiology and diagnosis of the patient’s condition, CR records were taken at an increased vertical dimension of 1 mm. Casts were mounted and a diagnostic wax up was completed for the anterior teeth. A posterior denture tooth set up was completed on the same casts. After patient approval, anterior teeth were prepared and provisional restorations were fabricated. A jig in the posterior region helped transfer the planned vertical dimension on the articulator to the patient. Posterior teeth were extracted and immediate interim mandibular and maxillary partial dentures were delivered after anterior provisionals were completed. The provisional restorations provided function and esthetics while the increased vertical dimension, plane of occlusion, and functional movements were evaluated.
After three months of healing, a secondary wax up of the posterior teeth was completed. Radiographic and surgical guides were fabricated. A CBCT evaluation was done. AstraTech Osseospeed implants were placed at sites #16,15,14 and #24,25,26 with a concurrent right lateral sinus augmentation. Implants were also placed at sites #36, 34, 44, 46. After three months of healing, all implants were uncovered and direct screw-retained implant provisionals were fabricated. All provisional restorations were adjusted to train the soft tissue, evaluate esthetics, phonetics, centric and eccentric tooth contacts. The goal was to transfer this information accurately to the laboratory so the final outcome was predictable. Investing more time in the provisional restorations reduced the chance of adjustments or remaking the definitive restorations.
After the patient was satisfied with the provisional restorations, the task was to transfer the information to the laboratory so definitive restorations have similar esthetics and function. To capture the soft tissue architecture, customized impression copings were fabricated using pattern resin. This prevented any soft tissue collapse immediately after removal of the provisional restoration and it was less likely the definitive restorations will be under or over-contoured. After material shrinkage, the resin was sectioned and the impression copings were reluted intraorally. A final open tray impression was taken using heavy and light-bodied polyvinylsiloxane capturing both implants and tooth preparations. Alginate impressions were taken of the provisional restorations and these casts were cross-mounted to the master casts using the screw-retained implant provisionals. This allowed the technician to fabricate definitive restorations that followed the plane of occlusion determined by the provisionals. In addition to a facebow transfer, the cross-mounted casts of the provisionals provided the technician with information regarding the occlusal cant, length, angulation, size and shape of the restorations determined by the practitioner and the patient. Metal frameworks were tried in to determine the fit, marginal seal and proper support for porcelain. Definitive restorations were tried in and occlusion, contacts, fit and retention were checked. Ceramometal crowns on #13, #12 and fixed dental prostheses from #11-x-22-23 and #33-32-x-42-43 were cemented with a resin-modified glass ionomer cement. Posterior implant screw-retained splinted restorations in the maxilla from #16-15, #25-26 and single screw-retained crowns at #14, #24 were torqued in. Mandibular implant restorations from #34-x-36 and #44-x-46 were also delivered. Screw access holes were filled with teflon tape and composite. A nightguard was fabricated for the patient to minimize risk of porcelain chipping and fracture. Frequent recalls and maintenance for this patient was crucial to prevent the recurrence of caries, periodontal disease and prosthetic complications.OH
Dr. Siu is a board certified Prosthodontist practicing at Dr. Mark Lin Prosthodontic Center, Markham Family Dentistry, and Foresthill Prosthodontists.
Oral Health welcomes this original article.
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